Ball gyro horizon



April 19, 1938. R. GlLLMoR Re 20,701

BALL GYRO HORIZON 7 original Filed Decfle; 1931 v 2 sheets-sheet 1 y INVENTOR H/S ATTORNEY.

Reuma Apr. 19,1938

PATENT oFFicE BALL Grao noRIzoN l aennaida animar, Great Neck, IlN. Y.. signor to Sperry Gyroscope Company, Inc., Brooklyn,

N. Y., a corporation of New York original No. 1,988,591, med .Tammy 2z, 1935,

Serial No. 581,936, December 18, 1931. Application for reissue October 29, 1936, `Serial No.

'I'he invention described in this specification is an artificial horizon or gyrovertical of a typel suitable for use in airplanes as a means of indicating the attitude of the airplane to the true horizon with respect to both horizontal axes.

It is nowwell known that the gyroscope Aprovides the only feasible method for continuously:

giving an indication of the true horizon on an airplane when the ground is obscured. Various forms of pendulums have been proposed for this purpose but all of them are rendered impractical by reason of the fact that, under the influence of. the acceleration and vcentrifugal forces tol which the airplane is subjected, all forms of pendulums except those which are gyroscopic take up a position -which is theresultant between the acceleration of gravity and the acceleration of the plane by reason of change of speed or change of direction.

,2o lThe gyroscope solves this problem by the introduction of an indirect or loose gravitational control; that is to say, the gyroscope provides a practicable means for obtaining a very long period of oscillation which responds very slowly to disturbing forces and, as these disturbing forces are constantly beingY reversed, the gyroscope deviates only slightly from the true vertical and is directly restored without oscillation by a source of power.

y 1n using the gyroscope as a means of indicating the horizontal on an airplane, three fundamental problems are involved. These are (1) to convert the gyroscope from a spiral oscillating gym-pendulum into a straight indicating aperiodic device'of long period, (2) to arrange the gyroscopic system in a manner which will providethe pilot with a direct indication of the lateral and longitudinal attitude of his plane to the horizon, (3) vto make the device extremely 40 simple and reliable soY that the pilot can rely upon it under all conditions. l

One object of my invention`is to accomplish the solution of these fundamental problems with i the least possible apparatus and in a way which will permit the pilot to see all of the operating parts and especially the rotating member and, therefore, to know at once vwhen any derangement has occurred which has stopped the rotation of the gyroscopic member; Y

- Another important defect which is overcome by the present invention is that prior gyroscopic horizons, while satisfactory foryordinary flying,

. could not be used for stunt flying, including loops and barrel rolls. While it is possible to so arrange the clearances of a gimballed gyroscope 23 claims. (ci. 33-204) that loops and barrel rolls may theoretically be accomplished, it i's found in practice that with all gimbal ring constructions the apparatus will sooner or later get into a position where the gimbal rings are crossed or twisted so as to cause 5 violent precession of the gyroscope and yupset the same, thus rendering' it inoperative for the time being. By the present invention all gimbal rings which directly support the gyroscopic element are eliminated andthe three degrees rof freedom se- 10 cured by a single external universal bearing, providing freedom about the spinning axis and freedom about both horizontal axes without the use of the usual rotor bearings' and gimbal ring bearings. Preferably, also, the indicator on the gyro 45 Aelement is of such a character that it may be seen equally well from either side of the instrument so that although the instrument is only visiblefrom the front, the visible level indicator remains in view even though the airplane may turn completely over as in a loop the loop.

Referring to the drawings,

Fig. 1 is a view of the face of my instrument showing the means for indicating to the pilot the attitude of his plane to the horizon. 25

Fig. 2 is a section ofthe same on line 2-2 of Fig. 1.

Fig. 3 is a sectional view of the ball or gyroscopic member oi' the horizon, also showing a modification. 30

Fig. 4 is a vertical section of the instrument.

Fig. 5 is an alternative form of the device providing means for indicating the relation of the airplane to the vertical.

Fig. 6 is a sectional detail taken on line 6 6 35 of Fig. 4

Fig. '1 is a vertical section of the annular ,chamber 2, showing the air channels there-v through.

l is supported on a nlm of air in the spherical annular chamber 2,'which provides in effect a continuous or upper and lower bearings for the ball (Fig. 4), leaving the front of the equatorial section thereof visible. The annular chamber is 45 supported on a lateral horizontal axis in the balll bearings 3., 'I'he ball bearings are carried in a fork 4, and the fork is carried on a longitudinal horizontal trunnion l0 in the anti-friction spaced bearings 5 and 6. The rearward of said bearings 50 may be formed in the back plate 3B, while the forward bearing 5 is supported in a bracket 42 rising from a forward extension 39`of the plate 38.y The ring or rotor bearing casing supporting the ball is made pendulous as by a mass 2 and, M

as the ring is suspended freely in ball bearings around both horizontal axes on trunnions 83, it will hang in the true vertical when not subjected to acceleration forces. The whole device as shown in Fig. lis'monted in the plane with the axis of the fork fore and aft, i.` e., coincident with the longitudinal axis of the plane. To avoid violent swinging of vthe pendulous gyroscopic member around the longitudinal axis, I attach swing quickly around the axis of the fork is reto the shaft fork light vanes 1 which are enclosed in the chamber 8 secured to plate `38 with very small `clearance between the vanes and the walls of the chamber. Therefore, any tendency to slsted by the slow escape of the air between the vanes and the walls of the chamber, thus damping any violent movements but at the same time not interfering with theaccurate settling of the supporting cup inv the true vertical.

For driving the ball, I introduce air through a hole and filter chamber 9 in back plate Il and thence through the hollow passages I Il and Iiinl the fork to transverse and axial bores '6l andi in trunnion 6I to tangential air jets I2 in the spherical supporting ring. Annular channels 6I and BI' adjacent the jets permit the ready escape experience, however. that even though supporting air is not supplied, the rotation' of the ball will wipe air between the surfaces of the ball and the supporting ring, thus creating a supporting film.

, The arrangement of air jets shown in Fig. 2 `will produce a high velocity of rotation of the ball around an axisat right angles to the plane of the paper. .To insure that the ball will always rotate around the same axis, I giveit a major axis by making it'hollow shown in Fig. 3, and

to insure that it starts rotation on this major axis I either make the ball slightly pendulous or I make the hollow chamber 3l of greater dimensions axially than diametrically and of circular cross secv tion diametrically. The cavityis also preferably tapered atthe bottom. As shown in the drawings, the cavity is substantially pear-shaped tapering toward the bottom and of greatest diameter near the middle. I then place in that chamber a globule 36 or small amount of mercury or other heavy liquid, i. e., muchless liquid than is necessary to flll saidchamber. When not rotating, the globule of. mercury will find its I'way to lthe small vrecess in the end of the chamber-and will thus make the ball pendulous, causing the ball to settle in that position as rotation ,ceasesl and causing it to assume that position (with its spin axis vertical) as it is beingspunfup. When `brought up to speed, the mercury is thrown out vby centrifugal force and distributes itself evenly around the equatorial plane ofthe ball, thus mak'- -ing the-ball non-pendulous. The amount of pendulosity can be governed accurately by the shape of the' bore.

By emplcyinga small amount of liquid within a symmetrical cavityI in the ball, I also achieve another very important purpose by eliminating a serious drawback to the ball type, air Supported vgrees of freedom are originally spun up about any spin axis, i.. e., the axis of'maximum moment of inertiaY or maior axis, the ball will nutate. While such a phenomen is observable in an ordinary gyroscope, it is not serious because itis speedily damped out by friction. In thecase ofv the air supported ball gyroscope, however, the problem of eliminating nuta.- tion'in a reasonable time is serious on account of the extreme freedom of support of the gyrcscope.

I have found, however; that by placing a small amount of liquid within the hollow bore in' the` ball,v .any original` n'utation is speedily dissipated or damped by converting into energyY of spin.

. To this end, the only requirement is that the only aids about which the fiuid can spin with an unbroken symmetrical free surface is the normalv axis of spin of the ball, so that if the ball is started with an initial nutation, the inertial reaction of` the fluid in g its unstable position is such as to transfer thev nutation energy into spin energy about the spin axis. ASuch a. phenomenon is not conned to the ball gyro with a vertical spin axis. In'any case,'.the amount of fluid. which is critical is that amount which will not provide a symmetrical free surface about any other axis than the desired axis of spinning. It may also be observed that by using a fluidy such as mercur which has a greater density than the density o the-steel'or brass rotor,the moment of inertia of the ball is increased when spinning.

The equator of the ball, the plane of` which lies perpendicular to the major axisI of bore 35 and winch is engraved with an `essny distinguishable line or marking, is made tosekthe true horizon bythe centralizing action ofthe driving airjets. To those who are familiar with the art, it will vbe seenthat once the ball is started rotating, any departure of the ball from the axis of its driving jets will result in" components from those driving jets which will result in precessing the axis of the ball into the axis of the driving jets by the -shortvest path and without oscillation. Inother words,

-I have, by the arrangement shown in Fig; 1, an extremely simple,ape1'iodic gyroscope, gravitationallycontrolled, which requires no means of damping other than the, jets themselves, which `iets would be necessary in any case i'rV the purpose of driving the ball. j

It will also be seen that by this construction I have succeeded in obtaining a horizon indicator which may be used in stunt ying as Well as in ordinary ilying,l since it will be unaffected by maneuvers in the airno matterhow involved. No

'gimbal rings are employed directly, but the .ball

gyroscope is floated in an air support which gives it freedom about its vertical spinning axis and about both horizontal axes.

As a means of indicating to the pilot the attitude of his planeLto the horizon, I mark the equator of the ball in some easily distinguishable manner as by a bright red line, as shown at i3 in Figs. 1 and 4. Meridional lines 45 may also be provided so that the aviator may tell whether the ball isspinning or not. Such lines may also be used tofurnish a valuable indication of the rate of rotation of-the ball.' For instance, if only one meridional line is employed, this line will be seen as a icker even at fairly high speeds up to the of tne'instrumentwmeh a nxed to the airplane as j -ingoccura -I also engrave on the face plate 3| l f a line'll. I-also engrave on the spherical ring f horizontalindex lilies Il and i6.

Assuming'that the line i3 engravedonthe 745y equator of the ball is coincident with the true horizon and that the device is placed on the instrument board in front of the aviator, it will be seen that a diving movement of the plane would result in raising theiine I4 engraved on the face plate above the line I3 on the bail,and a'climbing attitude of the plane wouldvresult in depressing the line on the face plate below the line on the equator of the ball. Therefore, in controlling his plane around the lateral axis, the pilot would only need to remember that he must move his controls in such manner as to restore the line I4 engraved on the face plate to the line I3 engraved on the bali. This action will be instinctive and as easy as flying with the view of the natural horizon. The same would hold for tilting of the plane around the longitudinal axis; that is to say. a position where the right wing is down would be indicated by a downward tilt to the right of theline engraved on the face plate with respect to the line on the ball, and the pilot would oniyneed to memember that he must restore the one to the 'other by moving his controls to the left.

It should also be noted that the visibility of the equatorial line I3 is unaffected by any looping the airplane may do. A complete loop of the gyroscope will have the effect of turning the supporting trunnion' III through an angle of 180 around the ball so' that the ball will be, viewed from the opposite side. This, however, will make no difference in the indication given, since the equatorial line will remain in position, the ball, however, revolving in this instance in the opposite direction with respect to the plane but the same grip on the ball around the normal axis of rotation than around any other axis and'increasing the rate oi' rotation. It will be seen by those familiar with the art that the rate at which the axis of the ball is restored to the axis of the jets is governed by the relation between the torque of the jets around the axis of rotation 'to the torque which the jets are able to produce on the ball around other axes, i. e., the period varies directly as a function of the rate of rotation and inversely as a function of the erecting couple. Moreover, the period of the gyroscope may be regulated so as to give the best results without being restricted to using an erecting torque sufiiciently strong to overcome gimbal friction, as in the ordinary gimbal supported gyros'cope.

-son I may employ a gyroscope with a. much longer period than a gimballed gyroscope because I have reduced friction about horizontal axes to al minimum. A

.The arrangement shown in Fig. 1 accomplish an additional desirable objective in that it provides a simple banking indicator, i. e., ameans Ifor indicating to the pilot whether or not he has the correct bank which will prevent skidding or slipping. This is accomplished lby the simple expedient of engraving lines on the face of the spherical ring as shown at I3 and IB- in Fig. 1.

The spherical ring is a pendulous member.

Therefore. if the banking is correct,-the lines I6 y For this reaout by other means.

and I6 on the ring should stay in coincidence withr the line I4 on the "face plate of theinstrument. When turning right, a condition producing skidding would be indicated if the right hand line I6 on the spherical ring should be above the line I4 may 'be provided either by venturi or pump, con- 'nected in such manner as to produce a vacuum Within the casing of the instrument orby a positive pressure. The vacuum type of driving the instrument is shown in the section elevation in Fig. 4, the air being withdrawn from the casing 33 through tube 34.

In order that the instrument may be readily taken apart and inspected, I prefer to attach all the bearings and other parts of the gyroscope to the back plate 3B of the casing 33. The back plate is shown as providedat the bottom with a forward extension 39 having a T-shaped head 40 engaging -a trackway in the bottom of the casing 33. The base plate 38, therefore, may be slid inwardly with the T head 40 in the trackway until the shoulder 4I thereon bears against the end of the casing 33, and the inner edge of the bracket 42 which supports the inner ball bearing 5 rests against the shoulder 43 on the base.

'Ihe alternative form of the device shown in Fig. lrinvolves the use of a bali II supported on an air film Ain a cup I3, the cup in turn supported in gimbal bearings in a fork I9, and the fork in turn supported in gimbai bearings in a manner similar to that shown in Figs. 1 and 2. In the arrangement shown in Fig. 5, the gyros copic member is covered by the face plate (not shown) of the instrument, and an image of the top of the ball is reected in a mirror 2l) pivoted on axis 40 and adjusted by knob 4I. On this mirror are engraved lines 2|, 2| which represent the airplane. The axis of the ball is indicated by a bright spot 22. The position of the pendulous cup is indicated by cross wires 23. As the image of the axis of the ball in relation to the airplane and to the cup is shown by reflection in the mirror, thepilot is provided with a direction, indication of departures of his plane from the true vertical. by an incandescent light 24. As in the main f form, the `correct banking angle is also indicated by comparing lines 23 and the airplane instrument 2|, 2|.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my `invention, togethery with the apparatus which I nowconsider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is. only illustrative and that the invention can be carried Also, while it is designed to use the Ivariousfeatures and elements in the combination and relations described, some of these may be altered and others omitted without ,interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to -secure by Letters Patent is: I

'1. In a gyro artificial horizon, a ball, a cup for supporting said ball on an air nlm; and an air 'I'he top of the ball may be illuminated Jet insaid-cup/for spinning said ball about a verquantity of heavy liquid sealed in said bore for ticalaxia' Wthepurposespeciiied.

2. In a gyro artificial horizon. a bail, av cup for supporting said ball on an air film, means for pendulously mounting said cup, and an air Jet in said cup for spinning; said ball and maintainingthe spinning axis vertical.

3. In a gyro articial horizon for aircraft. a ball, a cup for supporting said ball on an air illm.- an air jet in said v'cup for spinning said ball about a vertical axis, said ballhaving an equatorial ring and a cooperating index on a fixed part ofthe aircraft.v

4. In a gyro artiilcial horizon for'aircraft, a ball, a c up for supporting said ball on an air lm, means for pendulously mounting said'cup; an air .iet in said cup for spinning said ball and maintaining the spinning axis vertical, said ball having an equatorial ring, a cooperating index on a fixed part of the aircraft to show pitch and 'lateral inclination, and a second index on said pendulous cup cooperatingfwith said other indicators to show the correct banking angle.

5. In a gyro articial horizon having a easing,A a ball-like rotor. upper and lower spherical bearings for the ysame,.a penduious support for said bearings universally mounted in said casing, an

equatorial ring on said ball visible from the front of the instrumentto show hoxizontality in both planes, and cooperating indices on said casing against which said ring may be read'.

6. A gyro horizon indicator comprising a casing havingl a Vtransparent front window, a gimbal member supported only at the back of said casing for oscillation about a horizontal axis, a rotor bearing ring pendulously .iournalled in said member for oscillation about a second horizontal axisV normal to said ilrst axis, `and a ball-like rotor peripherally supported in said ring for spinningy and precessing and having an equatorial marking and a normally horizontal mark at said front window, whereby the attitude of -the craft mayf be observed about both horizontal axes.

7. A gyro horizon indicator comprising a cas'- ing having -a transparent front window, a gimbai member supported only at the back of said casing for oscillation about a horizontal axis, a rotor bearing ring pendulously journalledin said member for oscillation about a second horizontal axis normally to said rst axis, and a ball-like rotorA peripherally supportedv in said kring for spinning and precessing and having an equatorial marking, a normally horizontal mark at saiiil front window, and an index on saidring cooperating with said other two markings, whereby the attitude of the craft may be observed both with respect to the horizon and the correct banking angle.

' il.A In a gyro artiilcial horizon, a ball-like rotor.

having an axial bore closed at both ends, said a lower heinisphrical bearing for the same, an index on the upper pole of the ball, a mirror above the ball and angularly positioned to provlect the image of the index forward, and coop-- erating markings on said support and mirror to show inclination vand banking. 1

9. In a gyro artiilcial horizon, a ball-like rotor having'an axial bore closed at least at the bottom. s said bore being of greatest diameter near the' middle and tapering toward the bottom, andy a small quantity of huid in pose specified.

`l0.- In'a rizon, a' ball-like rotor having an axial bore closed at both ends; said bore being of greatest diameter near themiddle and tapering toward'each end, and a said boreiior the pur- Y senor 11; In a gyro articial horizon, a ball, a cup for supporting said ball on an air nlm, means lor pendulously mounting said cup, damping means for said pendulous cup. and an air .iet

in said cup for spinning said ball and maintaining the spinning axisv vertical. f 12. In a gyro articial horizon having a casing.l a ball-like rotor, upper and lower spherical bearings for the same, a pendulous support for said bearingsuniversally supported in said ball-like rotor, upper and lower spherical bearings for the same, a universal pendulous support for said bearings, an equatorial ring on said ball visible from the front of the instrument to show horizontality in both planes, a cooperative index ilxed on the craft, anda second index on said penduious support cooperating with said two other markings to howjhe correct banking anld.- In a gyro artincial horizon for airplanes,

a ball rotor, a meridional ring around the same .furnishing @universal air nlm nearing therefor,

athwa'rtship axis, and an equatorial ring on saidy ball visible normally through said front opening but equally visible through the other opening in case the airplane loops or somersaults.

1 5. In a gyro artiilciai horizon `for airplanes, ay

ballrotor, a meridional ring around the same` furnishing a` universal air film bearing therefor, means for pendulously supporting said ring, and means on said-ring for spinning said rotor about a vertical axis.

18. In a gyro artificial horizon, a ball, acup for supporting s aid ball on an air film, means for pendulously mounting said cup, and an air jet in said eup'ro'r spinning and. erecting the bau, said l spinning force being of much greater magnitude than the erecting force to give a long period.

17. A'ball' type gyroscope having an axial bore 'ofen-ema; ers section closed an the ends, and` a quantity of liquid sealed therein, whereby nutationis suppressed.

18. A ball'type Eyroscope having a cavity therein having its greatest dimension along the desired spin axis'of the ball and of circular cross section.v

and a heavy liquid'therein of an amount insumclent to provide a symmetrical free surface about any other than said spin axis.

19. In a gyro artificial horizon, -a ball-like rotor porting said ball `on an air illm, and an air jet for spinning said ball'about a vertical axis.

21. In a gyro artificial horizon having a casing,

a ball-like rotor, upper and lower spherical bearings for the same. said `ball having n utation damping means within the same, a rpendulous support for said vbearings universally mounted in said casing, an ring on said ball visible from the front oi.' the instrument to show hori- .quantity of liquid therein, a cup for supzontality in both planes, and'cooperating' indices on said casing against which said ringmay be read. l v

22. In a gyro artificial horizon for aircraft,vv a ball, a cup for supporting said ball on an air film. an air jet in said cup for `spinning said ball about a vertical axis, said ball having an equatorial ring and a bore of circular cross section having its major axis perpendicular to the plane of said ring, and a cooperating index on a ilxed part of the aircraft.

23. In a gyro artlcial horizon for aircraft. a

bal1,a`cup for supporting said ball for spinning cooperating index'.

bal at the rear thereof, said ball having an eduaf torial ring and a cooperating index on a. xed portion of the craft whereby no part of the gimbal means extends between said ring and said REGINALD Ef GILLMOR. 

